package bishi.day17_5_13;

import java.util.Arrays;
import java.util.Scanner;

/**
 * @author 是阿秋啊
 * @date 2022/05/13 10:44
 **/
public class Yang_Hui_deformation {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int n = sc.nextInt();
            if (n <= 2) {
                System.out.println(-1);
            }else if (n % 2 == 1) {
                System.out.println(2);
            }else if (n % 4 == 0) {
                System.out.println(3);
            }else {
                System.out.println(4);
            }
        }
    }
}